Interaction between substitutional and interstitial solute atoms in α iron studied by isothermal mechanical spectroscopy

The interaction of interstitial nitrogen with substitutional alloying elements has been studied by measuring the Snoek relaxation in very dilute Fe–X–N ternary alloys (X: V, Cr, Mn, Mo). Isothermal measurements by the sub-resonance forced-vibration technique have revealed characteristic influence of substitutional solutes on the Snoek relaxation, which can be understood as trapping of N atoms at neighbouring sites of X atoms. The interaction energy has been evaluated by comparing the relaxation profiles observed experimentally with those calculated theoretically. The values thus obtained are of the order of 0.1 eV, with the magnitude being larger for elements of smaller group numbers, and are similar to those in the γ and liquid phases.